On Friday 10 February 2017 21:54:45 Jon Elson wrote: > On 02/10/2017 03:59 PM, Jim Craig wrote: > > So my questions are as follows. What type of power supply would I > > need to use for doing small hole EDM drilling? Can I use a tig > > welder as the power supply and control pulsing with LinuxCNC driving > > an external IGBT? > > TIG is constant current, and generally way more than you > need. IGBTs are good for 400+ Volts, MOSFETs make more sense > below that. > > > Could I use the Mesa THC to control gap of the electrode to the > > workpiece? > > > > It appears that spindles don't need to rotate very fast. What type > > of rpm do the spindles typically run at?
What I've done is A, rank amateur, and B, at 150 to 200 rpms so as not to be pitching the dielectric fluid, usually distilled water, all over. But whats the hole diameter and depth again? If the hole is deep compared to the diameter, you'll be going down less than the hole diameter before the sludge shorts you out, so figure on doing a peck cycle, and figuring out how to flush the hole clean before putting the electrode back in the hole. If you can figure out how to feed dielectric into the right sized hypo needle, that would keep the hole flushed and would cut lots faster. But I've not managed to come up with a workable idea for that, I'm usually done by the time I've noodled out an idea I could do with what I had on hand. Best idea so far as do a peck, going about a thou deeper per peck, and doing the peck at a high enough speed to keep the mix well agitated so the sludge would be squirted out on the downstroke, and the upstroke would bring fresh water to dilute the sludge, in at a high enough speed to keep it well stirred. Fast its not going to be. The last time I was working in a deep hole, I was burning the center web out of a couple broken off in the hole 6-32 taps. IIRC it was much of a day for each broken tap cleared out of the hole. But it still beat starting all over by $25 worth of steel and 3 days putzing around to make it again. > The problem is EDM is very slow. Your holes would take at > the least, several minutes each. But, they'd be pretty clean. > You ought to get in touch with Ben Fleming, he demoed a > pulser EDM system at some of the CNC workshops in Ann Arbor > a few years ago. > > http://www.homebuiltedmmachines.com/build-a-pulse-edm/ > > He has a book and a circuit board, and you can build it in a > couple weekends. It was VERY cool to watch it work! > > Jon > > ---------------------------------------------------------------------- >-------- Check out the vibrant tech community on one of the world's > most engaging tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
